The lion's share of political ad spending on the Web goes toward the search market dominated by Google. Still, 25% of Web ad spending may go to social networks this election, says Pachter, with the number expected to rise in coming cycles. That could reverse recent negative trends for Google competitors. According tocomScore data, Google's display ads increased 12% year-over-year in August, while Facebook posted a 20%-plus decline.

For Facebook, which is forecast to earn roughly $5 billion in 2012 revenue, according to analyst estimates compiled byBloomberg, a share of such revenue numbers won't make a big impact. However, Pachter says political ad spending could be important for Pandora, which he estimates will earn up to $430 million in fiscal 2013 revenue. "It's meaningful," he says of prospective political revenue for Pandora. "I think it moves the needle even if we are talking about single digit millions," Pachter adds.

Pandora chief executive Joe Kennedy hinted as much in Pandora's second quarter earnings on Aug. 29, noting that after a modest impact on second quarter earnings, he expects a greater third quarter earnings benefit from campaign ads. Kennedy cautioned political spending is unlikely to be a key earnings driver in the near-term, but acknowledged it could reveal the network's relevance to advertisers.

"It's not an insignificant amount, but it's not a huge amount either," Kennedy said of an earnings boost. "The fact that we enable the ability to target geographically and demographically is highly attractive to political advertisers just as it is to virtually every other form of advertising," Kennedy told analysts.